Найдите сумму первых пятидесяти членов арифметической прогрессии An,если известно ,что: a1=2 , a50=147

английский язык 11 класс помогите

Choose the correct answer.

1 I should buy a ____ because I travel a lot and it would make things easier for me.

a desktop b laptop c keyboard

2 I don’t like typing on this ____. I am going to get a new one.

a keyboard b screen c scanner

3 You can use a ____ to copy all your old photographs on to your computer. a

keyboard b scanner c screen

4 My brother spends too much time on the ____. He needs to find a hobby outdoors.

a printer b online c internet

5 I love my new monitor. The ____ is 17 inches long!

a mouse b printer c screen

7 Choose the correct answer.

1 Adam had ____ finished getting dressed when he realised that the dinner had been cancelled.

a just b already c since

2 I haven’t seen her ____ we were in university.

a soon b already c since

3 It is a good idea to do some stretches ____ you play sport.

just b already c before

4 You shouldn’t swim ____ you eat a big meal. a for b after c before

5 You should be careful with the equipment ____ you go to the laboratory.

a soon b just c when

6 I can’t believe he finished his homework ____! He started only an hour ago.

a already b just c before